Here is a short video tutorial on how to add an image (eg logo, eyes, tattoo ..) to a texture in Blender. Hope it help to you ...

How to morphing shape and texture quickly in Blender. Transforms objects both in shape and in material. Subscribe!

You just need a little practice with Blender 3D. If you wish to add textures to your meshes, check out the Roblox Corporation's tips.